Just showing up and attending classes has worked well for me. If I feel uneasy I tell the instructor "My dojo de-emphasizes breakfalls, please be a bit careful with me." I've only sat out once, and that was because it was apparent at a glance that the class would require more aerobic endurance than I could possibly manage.

The tatoo wouldn't be a problem for us. I did have one funny experience with henna temporary tattoos. An unfamiliar junior student went to attack me--I was calm up until the point where she opened both hands to grab and there were eyes on her palms looking at me! I flinched, she overran me....